Identification
A long white day is followed by a Doji that gaps in the direction of the trend. Then a black day occurs gapping in the opposite direction with no overlapping shadows.

The Psychology
In an uptrend or within a bounce of a downtrend, the market gaps up but does not continue it's upward movement. Instead enough bears step in to bring supply and demand back into equilibrium and the stock churns in place. This isn't necessarily bearish, but it's certainly less bullish. The pattern is confirmed by the next day's gap down and drop.

If you can handle the volatility, DAL provided a decent entry on a short when the stock formed a bearish Abandoned Baby formation at resistance. If this pattern had formed in a steady uptrend, it would be very risky, but given that it formed at a previous high, the reliability of the pattern increases.